1. Field of the Invention
This invention relates to paper web formation analyzers. Such structures of this type, generally, can be employed both on paper machines operating at high speed and on cut samples as a desk top unit, so as to unify formation evaluation for both situations.
2. Description of the Related Art
It is well known, in the paper making industry, to make use of various sheet material characteristic measuring devices. Exemplary of such prior art is U.S. Pat. No. 3,936,665 ('665) to J. F. Donoghue, entitled "Sheet Material Characteristics Measuring, Monitoring and Controlling Method and Apparatus Using Data Profile Generated and Evaluated by Computer Means". While the '665 patent teaches the control of primary paper properties such as basis weight, moisture and caliper, the focus of the '665 patent is more for control of primary properties than in evaluating sheet formation. Consequently, a more advantageous analyzer, then would be presented if sheet formation could also be evaluated.
It is also known, to employ a single point measuring technique to measure sheet formation as well as other primary paper properties, such as, paper strength. Exemplary of such prior art is U.S. Pat. No. 5,104,488 ('488) to L. M. Chase, entitled "System and Process for Continuous Determination and Control of Paper Strength", U.S. Pat. No. 4,707,223 ('223) to J. Sabater et al., entitled "Apparatus for Measuring the State of Formation of a Sheet of Paper", U.S. Pat. No. 4,648,712 ('712) to I. F. Brenholdt, entitled "Apparatus and Method for Analyzing Parameters of a Fibrous Substrate", and U.S. Pat. No. 4,644,174 ('174) to R. J. Ouellette et al., entitled "Apparatus for Analyzing the Formation of a Paper Web". While the '488, '223, '712, and '174 patents teach the use of an apparatus to measure sheet formation, these employ a single point sensor to infer overall sheet formation. This single point sensor, typically, is either fixed or scanning, but at any point in time, only a single area is being studied. Consequently, a still further advantageous analyzer, then would be presented if a wider inspection area can be studied, while giving a quantitative picture of what is going on with respect to a paper formation.
It is apparent from the above that there exists a need in the art for a paper web formation analyzer which can provide a wide inspection area while giving a better quantitative picture of paper formation, but which at the same time is capable of being used both on operating paper machines and on cut samples. It is a purpose of this invention to fulfill this and other needs in the art in a manner more apparent to the skilled artisan once given the following disclosure.